Primary CNS Lymphoma

Primary lymphoma of the CNS (PLCNS) is a rare, usually aggressive form of diffuse large B cell lymphoma (DLBCL) confined to the brain, meninges, eyes, or spinal cord. Secondary lymphoma of the CNS (SLCNS) represents CNS metastatic spread of systemic lymphoma, commonly via haematogenous dissemination. CNS lymphomas preferentially affect older individuals, and their incidence is increased in immunosuppression (with a more variable age onset). The imaging patterns in PLCNS and SLCNS typically differ but show substantial overlap and can be highly variable with an influence from immune factors. Advanced image sequences can contribute important information to the initial diagnosis of brain lymphoma, however tissue diagnosis remains mandatory before initiating combination chemotherapy due to a high risk of toxicity. This chapter focuses on imaging for the initial characterization, differential diagnosis, and post treatment follow up of PLCNS and SLCNS.